1. Field of the Invention
This invention concerns an automatic dispenser for paper towels which are severable from a continuous roll in the shape of predetermined length strips made available on the outside of the dispensing apparatus so that they can be subsequently torn off manually against a stationary blade located in a relatively hidden position within the device.
A number of types of paper towel dispensers are already known, adapted in particular to enable a manual pulling of the free flap which has remained accessible after a previous usage, and the "ripping" thereof against a stationary blade. A brake device is sometimes provided which is adapted to block the unwinding of the strip from the feed roll, after a certain length, thereby making it easier to tear off the paper to be used, whereafter a further clean flap of material may be allowed to project outside to be manually grabbed for a subsequent usage cycle. In other embodiments, a side crank or handle is provided for rotating the feed roll in the unwinding direction, in order to have available on the outside a paper strip of a desired length.
In any case, actuation is generally manual, while motorized actuation is usually a feature of fabric towel dispensers, where the higher cost caused by automatic controls and motor actuation seems to be justified by the different properties of the material, which is substantially reusable and lasts longer.
2. Description of the Prior Art
However U.S. Pat. No. 4,666,099 discloses an automatic dispenser for paper towels which, when activated in response to the proximity of a portion of a user's hand without the need of contacting the apparatus, dispenses a predetermined length of sheet material from a supplying roll of material by means of an electrical motor operating for a predetermined time.
Furthermore U.S. Pat. No. 2,839,345, with reference to another dispenser apparatus, although manually operated by means of a crank, discloses the presence of a re-setting button which is connected to a feed-limiting mechanism preventing a continued rotation of the crank, whereby only by pressing said button the mechanism is released and another portion of paper web can be dispensed, corresponding to the allowed rotation of the crank. To avoid a misuse of the apparatus the re-setting button is concealed from the view until the user has torn off across a knife the length of web originally dispensed and the button is exposed to be pressed again, thus causing the device to be in condition for operation. With this arrangement the knife or cutting blade is mounted on a lower portion of the housing in a position set back within the dispensing port.
It is also known from the prior part (e.g. U.S. Pat. No. 4,666,099) to use a photoelectric cell to control the dispensing motor. Also providing two separate means, such as a photocell and a push-button, for actuating the apparatus, thus allowing the operator to select which means to use, could be known or obvious to one having ordinary skill in the art.
However it is not really practicable to provide on the apparatus a means such as a selector in order that a user can choose at will the type of operation to be adopted, for both reasons of avoiding that a rather delicate device is made available to the public and subject to improper operations, and owing to the natural reluctance, from the users themselves, to contact with their own hands, often dripping or wet, parts of the apparatus already touched by other persons and possibly still carrying traces of water left by a previous user.
Furthermore it is preferable that the dispenser is usually operated by means of a photoelectric cell or proximity detector, except in case of failure thereof (e.g. owing to a possible misuse, like sticking on the photocell or anything that can intercept its light beam) where a subsequent user may be unaware of the situation and unable to operate the dispenser.